This invention pertains to a screw compressor. The invention preferably, but not exclusively applies to a screw compressor used to produce a pressurized air stream for pneumatic transport of bulk materials. In particular, the invention applies to a screw compressor designed to be attached to a silo vehicle.
Screw compressors are air compressors that work on the positive displacement principle. They have advantageous characteristics as compared to other compressors that make them especially suitable for the pneumatic transport of bulk materials. This applies in particular for so-called dry-running screw compressors in which the screw rotors, which are synchronized by means of a synchromesh gear, do not make any contact with each other nor with the surrounding housing parts. Thus, there is no need for lubrication in the compression space so that this space can be kept oil free, preventing any oil contamination of the pressurized air. Also, since the rotors run without touching one another, there is no wear in this area that could reduce their lifespan. No abrasion arises that can contaminate the conveyed air. As a result of their operating characteristics, screw compressors are suited mainly for the achievement of high compression ratios. They are insensitive to short term pressure increases that could be caused by pluggage of the pipelines carrying the pressurized air. Finally, they are lightweight and compact, which makes them suited especially for mobile use, for example in silo vehicles.
In known screw compressors up until now, in particular for those used in silo vehicles, the drive gear for the rotors is located at one end and the synchronizing gear is located at the other end of the rotors. Oil lubrication is thus needed both at the pressurized end as well as at the suction end of the rotors. The intake of air is done through a filter and/or a muffler, which are designed as separate units from the compressor housing and are connected to the compressor housing through an intake line that opens up into it in the vicinity of the suction end of the rotor housing and passes around the synchronizing gear. The presence of oil lubrication at the suction side of the rotor housing is undesirable since it increases he danger of contamination of the air with oil. The design of the intake filter and/or muffler separated from the actual compressor housing does not lend itself to a compact, robust and low-weight design, depending on the requirements.
The purpose of this invention is to enable a simpler and improved air intake and a compact design of the compressor by improving the design of the screw compressor in the area of the suction end of the compressor housing.
By locating both the drive as well as the synchronizing gear on the pressure side of the rotor housing, oil lubrication can be eliminated completely at the suction end of the rotor housing. Furthermore, the area of the housing cover on the suction side surrounding the shaft journals and their bearing arrangement on the suction side of the rotors can be used directly for the inflow of air into the compressor space. In this area, there is no danger of contamination of intake air with oil. An intake housing containing the intake filter and/or the intake muffler can be directly attached to the suction end of the compressor housing, resulting in a compact, space-saving design that is especially robust for mobile use.
One embodiment form of the compressor according to the invention is explained in more detail with the help of the drawings.